Abstract 17556: Effect of Spinal Cord Stimulation on Myocardial Flow Reserve in Patients with Severe Angina Pectoris

Abstract

Purpose: Spinal cord stimulation (SCS) relieves angina pectoris in patients with ischemic heart disease, but its mechanisms of action remain incompletely understood. The goal of this study was to determine whether short-term SCS therapy improves myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients with myocardial ischemia.

Methods: The study group consisted of 18 patients (16 males) ageing 59 to 84 years who had severe stable angina pectoris (CCS class 3-4 in 70%) despite optimized medical therapy, evidence of myocardial ischemia in non-invasive testing, but not being amenable to further revascularization. All patients had three-vessel-disease and prior coronary artery bypass Surgery. Nine had prior myocardial infarction. Patients with recent MI or ejection fraction <40% were excluded. Quantitative myocardial blood flow was measured with positron emission tomography (PET) and [¹⁵O]H₂O during rest and adenosine stress before turning the SCS device on (baseline) and again after three weeks of continuous therapy. At the same time points, endothelium -related MBF response (ΔMBF) to cold pressor test (CPT) was evaluated in 13 patients.

Results: There were no adverse clinical events during the study. Heart rate and mean arterial pressure at rest were comparable at baseline and after 3 weeks therapy (63±11 vs. 63±12 bpm and 93±15 vs. 95±14 mmHg, respectively). Global MFR significantly increased from 1,74±0,61 at baseline to 2,20±0,63 after 3 weeks therapy (p=0.03). This was associated with slight decrease in global MBF at rest (0,91±0,22 vs. 0,81±0,16 ml/g/min, p=0,068) and slight increase in global stress MBF (1,56±0,52 vs. 1,64±0,57 ml/g/min, p=0,125). In addition to global flow reserve, there was also increase in MFR after 3 weeks of therapy in the segments with reduced flow reserve (<2.0) at baseline (1.4±0.3 vs.1.8±0.5, p=0.01). There was > 20% improvement in MBF response to CPT in 6 of 13 patients after therapy, whereas only 1 patient had worse MBF response after therapy.

Conclusion: Short term SCS treatment improves myocardial flow reserve and endothelium -dependent vasodilatation in patients with ischemic heart disease and severe angina pectoris indicating that the treatment has anti-ischemic effects.